Hey, i'm just a guy and I develop applications and study at the same time, so I dont work...
In a lot of post I read words like IT jobs, 'editing code in production', could someone please explain me their meaning? Thank you

When people say production they usually mean the actual server that a website/web app/program is running and can be accessed by users. Usually when code is edited, it is edited on a local server/computer , NOT the production server, and then when it is tested and works it is put on the production server.

You don't want to be editing on the production server because if you make a mistake and break something, end users are affected.

Cheers :)

Best practice says you should have more than one environment / setup.

(Production)I have a server that has my public facing sites and databases

(Dev)I then have a replica copy of that server for testing new code on.

Thank you both guys!! Then it is what I already do because I write apps on my localhost and then I publish them... thank you again